Consumers use tissue products for a wide variety of applications. For example, various types of tissue products may be used, such as facial tissues, bath tissues, paper towels, napkins, wipes, etc. In many instances, various types of liquid-based compositions, such as softening compositions, lotions, friction reducing agents, adhesives, strength agents, etc., are also applied to one or paper webs of the tissue product. For example, a paper web is often softened through the application of a chemical additive (i.e., softener). However, one problem associated with some liquid-based compositions is the relative difficulty in uniformly applying the composition to the paper web of the tissue product. Moreover, many application methods are relatively inefficient and thus may result in substantial waste of the composition being applied.
For instance, many softeners are made as an emulsion containing a particular solids content in solution. However, such liquid-based compositions are often difficult to adequately apply to a paper web. In particular, when applying such a liquid-based composition, the paper web can become undesirably saturated, thereby requiring the paper web to be dried. Moreover, it is also difficult to uniformly spread the liquid-based composition on a paper web in such a manner to provide adequate surface area coverage. In addition, some softeners contain components that cause the liquid-based composition to be formed as a solid or semisolid. To facilitate application of these liquid-based compositions onto a tissue product, extensive heating may be required. Moreover, even after extensive heating, it may nevertheless be difficult to uniformly apply the composition to the tissue surface.
As such, a need currently exists for an improved method of applying a liquid-based composition to a paper web.
In accordance with one embodiment of the present invention, a method of applying a foam composition to a paper web (wet or dry) having a first surface and an opposing second surface is disclosed. The method comprises positioning a foam applicator adjacent to the first surface of the web. The foam applicator defines an extrusion channel through which the foam composition is capable of flowing. The foam applicator further defines a dispensing slot through which the foam composition is capable of exiting the foam applicator. In one embodiment, the foam applicator further defines a gaseous channel through which the gaseous stream is capable of flowing. When flowing through the gaseous channel, the gaseous stream can be accelerated therethrough.
The method also includes flowing the foam composition through the extrusion channel of the foam applicator. The flowing foam composition is impinged with at least one gaseous stream (e.g., air stream) to fragment gaseous bubbles contained therein before the foam composition is applied to the first surface of the paper web.
Depending on the type of foam applicator selected, the foam composition can be impinged with the gaseous stream before (internal) or after (external) exiting the dispensing slot. Moreover, regardless of the specific type of foam applicator selected, various geometric and/or process parameters may be controlled in the present invention. For example, in one embodiment, the distance from the initial convergence of the gaseous stream to the dispensing slot is from about 0.1 to about 12 inches, and in some embodiments, from about 0.2 to about 10 inches. Moreover, in some instances, the angle at which the gaseous stream impinges the foam composition is from 5xc2x0 to about 60xc2x0, and in some embodiments, from about 10xc2x0 to about 40xc2x0.
In addition, the method described above can also further comprise positioning a vacuum slot adjacent to the second surface of the paper web so that the paper web is positioned between the foam applicator and the vacuum slot. Such a vacuum slot can help draw the foam composition onto the first surface of the paper web.
In accordance with another embodiment of the present invention, a foam applicator system for applying foam to a paper web is disclosed. The system comprises a foam applicator that comprises an extrusion head defining an extrusion channel through which a foam composition is capable of flowing and an air channel through which an air stream is capable of flowing. The foam applicator further defines a dispensing slot through which the foam composition is capable of exiting the foam applicator. In one embodiment, the air channel and extrusion channel intersect within the extrusion head so that the air stream is capable of impinging the foam composition before the foam composition exits the dispensing slot. In another embodiment, the air channel and extrusion channel are configured such that the air stream impinges the foam composition only after the foam composition exits the dispensing slot.
Other features and aspects of the present invention are described in more detail below.